It has been proposed to measure angles of shafts, which rotate away from a reference position, to determine reference markers, rotary speed of a shaft, and the like, by use of sensors in which a magnetic element is coupled to the rotor cooperating with a magnetic field responsive element secured on the stator of the sensor combination. The rotor can be so constructed that a permanent magnet is included between two pole shoes, typically formed as sheet metals presenting pole surfaces, which have claws, the magnetic circuit being closed about an air gap between the claws of the pole shoes. The magnetic field, which passes through the air gap, is sensed by a magnetic field responsive element of the stator, located to be in magnetically coupled relationship thereto, for example in the vicinity of the stator. A system of this kind is described, for example, in German Patent Disclosure Document DE-OS No. 26 49 321.
Sensors which have been used employed, customarily, several pairs of claws distributed over the circumference. The claw pairs are alternately effective with respect to each other. It is difficult in such systems to obtain bipolar signals with low jitter, since only a single predetermined field direction toward the claw pole pairs is generated.